Answer:The height of the image is -6 mm.
Explanation;
Distance of the object form the lens = u = 12 mm
Distance of the image formed from the lens = v = 4 mm
Height of the object = 18 mm=[tex]h_o[/tex]
The magnification is given by :
[tex]M=-\frac{v}{u}=\frac{h_i}{h_o}[/tex]
[tex]h_i\& h_o[/tex]= Height of an image and object respectively.
[tex]M=-\frac{4 mm}{12 mm}=\frac{h_i}{18 mm}[/tex]
[tex]h_i=-6 mm[/tex]
The height of the image is -6 mm.The image formed is real and negative sign signifies that image is inverted.
